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<TITLE>Magic-8.3 Command Reference</TITLE>
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<H1> <IMG SRC=../graphics/magic_title8_3.gif ALT="Magic VLSI Layout Tool Version 8.3">
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<H2>zoom</H2>
<HR>
Specify rendering scale.
<HR>

<H3>Shortcuts:</H3>
   <BLOCKQUOTE>
      Key macro <B>Z<B> implements a zoom-out function. <BR>
      Key macro <B>z<B> implements a zoom-in function. <BR>
      Key macro <B>&lt;<B> decreases the vertical scale. <BR>
      Key macro <B>&gt;<B> increases the vertical scale.
   </BLOCKQUOTE>

<H3>Usage:</H3>
   <BLOCKQUOTE>
      <B>zoom</B> [<I>xy</I> <I>z</I>] <BR><BR>
      <BLOCKQUOTE>
         where <I>xy</I> is the scale in both <I>x</I> and <I>y</I>
	 dimensions (which cannot be set differently from each other),
	 and <I>z</I> is the scale in the <I>z</I> (vertical) direction.
      </BLOCKQUOTE>
   </BLOCKQUOTE>

<H3>Summary:</H3>
   <BLOCKQUOTE>
      The <B>zoom</B> command changes the scale of the 3D rendering,
      effectively moving the viewpoint closer to or farther away from
      the vertical axis origin. <P>

      Three-dimensional rendered views of layout usually exaggerate
      the vertical axis (like topographical maps of the Earth) to
      allow the vertical structure to be more readily viewed and
      understood.  The vertical axis scaling is therefore arbritrary,
      and may be set independently of the other axes. <P>

      Note that the <I>z</I>-axis value is represented such that
      it is independent of changes in the <I>xy</I> zooming.
      Key macros implementing zoom-in and zoom-out functions
      effectively change the scaling factor of <I>all three</I>
      viewing axes simultaneously, so that the vertical scale
      remains proportional to the horizontal scales.  This does
      not change the zoom value of <I>z</I> reported by the
      <B>zoom</B> command. <P>

      Without arguments, <B>zoom</B> returns the current scalefactors
      in both the <I>xy</I> axes (combined) and <I>z</I> axis.
   </BLOCKQUOTE>

<H3>Implementation Notes:</H3>
   <BLOCKQUOTE>
      <B>zoom</B> is implemented as a built-in <B>wind3d</B>
	window command in <B>magic</B>.  It overrides the
	default window client <B>zoom</B> command.  Note that the
	<B>wind3d</B> window is only available when magic is
	compiled with the OpenGL graphics option and invoked
	with <B>magic -d OGL</B>. <P>
	
	Note that macros of the <B>wind3d</B> window are hard-coded,
	and cannot be changed with the <B>macro</B>, <B>gmacro</B>, or
	<B>imacro</B> commands.  There is no "<TT>:</TT>" macro for
	entering commands; to enter commands from the command-line,
	use the <A HREF=../tk_path_name.html> <I>tk_path_name</I></A>
	command.  The default Tk path name of the <B>wind3d</B> window
	is "<TT>.magic3d</TT>".
   </BLOCKQUOTE>

<H3>See Also:</H3>
   <BLOCKQUOTE>
      <A HREF=scroll.html><B>scroll</B></A> <BR>
      <A HREF=view.html><B>view</B></A> <BR>
   </BLOCKQUOTE>

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<P><I>Last updated:</I> October, 2004<P>
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